//计算1/1-1/2+1/3-1/4+1/5.....+1/99-1/100的值，打印出结果
#include <stdio.h>

int main()
{
    int i = 0;
    int flag = 1;
    float sum = 0;
    for(i=1;i<=100;i++)
    {
        sum += (flag)*1.0/i;
        flag = - flag;
    }
    printf("%f\n",sum);
    
    return 0;
}